Inks used in printing on low-porous or non-porous print media, such as vinyl, provide a challenge with respect to generating an image with high durability, high chroma, and good lightfastness simultaneously without the need for an additional lamination step. Although lamination can provide improved durability and color gamut, it results in added expense (both through added materials and increased scrap and incremental labor costs) and slower turn around time. One approach to formulating inks for use in low-porous or non-porous media to achieve the above-described characteristics has been by increasing the pigment concentration in the ink. Unfortunately, this can decrease the durability of the image. Another approach has been to use higher chromatic pigments. Unfortunately, such pigments typically have much lower lightfastness and thus are not desirable for outdoor graphics, a common use for low-porous or non-porous media. A third approach to achieving the above-described characteristics has been adding solution resins. The addition of solution resins suffers from the drawback that these materials often increase the viscosity of the ink, thereby causing the inks to hit their viscosity limit and rendering the inks unreliable in many ink-jet printheads.
Accordingly, investigations continue into developing ink and ink set formulations that are capable of providing high durability, high chroma, and good lightfastness when printed on low-porous or non-porous media without the need for lamination.